drm/i915/tc: Check for TC PHY explicitly in intel_tc_port_fia_max_lane_count()

Check explicitly if the port passed to
intel_tc_port_fia_max_lane_count() has a TC PHY, instead of relying on
the default TC mode value set for non-TC PHY ports.
Reviewed-by: Mika Kahola <mika.kahola@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230323142035.1432621-7-imre.deak@intel.com

drivers/gpu/drm/i915/display/intel_tc.c

@@ -188,10 +188,11 @@ int intel_tc_port_fia_max_lane_count(struct intel_digital_port *dig_port)
 {
 	struct drm_i915_private *i915 = to_i915(dig_port->base.base.dev);
 	struct intel_tc_port *tc = to_tc_port(dig_port);
+	enum phy phy = intel_port_to_phy(i915, dig_port->base.port);
 	intel_wakeref_t wakeref;
 	u32 lane_mask;
 
-	if (tc->mode != TC_PORT_DP_ALT)
+	if (!intel_phy_is_tc(i915, phy) || tc->mode != TC_PORT_DP_ALT)
 		return 4;
 
 	assert_tc_cold_blocked(tc);